1. Field Of The Invention
The present invention relates to the protection against alteration of the amount imprinted on a check or other financial instrument.
2. Description Of the Prior Art
Various techniques have been utilized to protect against alteration of the amount imprinted on a financial instrument, such as a check. One popular approach has been to macerate the amount directly into the document. Indelible ink is absorbed by the shredded paper fibers, making it difficult to alter the amount. However, the use of maceration in machines to imprint checks, for example, on a continuous basis undesirably slows down the machine.
Safety papers have been used which have chemically reactive coatings which can change color or bleach out the color and reveal words, such as "VOID", to show that an attempt has been made to alter the document.
Other techniques have involved printing numerical characters against a background or field such as to make attempts to alter the characters readily detectable. Copending U.S. application Ser. No. 588,452, filed Sep. 26, 1990, entitled "Check Protector With Means For Printing The Amount In Bands Of Different Colors", prints each character in alternating bands of color to make alteration difficult.
These various types of financial instrument protection require the use of specialized printing equipment and/or paper.
It is also known to provide a standard message on a check that it is not valid over a predetermined amount. This message is typically pre-printed or applied as a standard background, border or prefix during the writing of the check with a mechanical check writer. But the predetermined amount is fixed and does not prevent alterations up to that amount.